Power and Control Cables over 32 Volts Installation in Plants Guidelines

Power and Control Cables over 32 Volts Installation in Plants Guidelines

The wire and cable provided and installed by the contractor shall be according to the contract drawings and this paragraph. All wire and cable (except thermocouple wire) shall be manufactured of stranded conductors. Solid conductor wire is not permitted. The minimum size for all power and lighting wire shall be #12 AWG, and for all control wire shall be #14 AWG, unless specified otherwise on the design drawings. In some instances, #14 AWG wire is too large for terminals on instrumentation and other electronic devices. In these instances, a smaller wire gauge will be permitted with approval from Air Products Design. Insulation color shall be provided as follows:

ApplicationSurface Color
AC PowerBlack
AC NeutralWhite
Equipment GroundGreen
AC Control or switched ACRed
DC Control/Power (over 32V)Yellow
Current TransformerBlue
Isolated ground (Iso-ground)Green

(with visible ends taped with orange tape as identified in the following)


Note:  In the preceding chart, wire colors white and green are mandatory by the NEC. No deviations may be made in these wire colors. All other wire colors are required. If the appropriate wire colors are not available, Company will accept taping visible ends of nonconforming wire with a minimum of 75 mm (3 in) of tape of the appropriate wire color except for colors white or green where the entire visible wire must be taped. When multi-conductor power and control cables are specified, standard manufacturer’s wire surface coloring is acceptable except for white and green as identified above. Once a wire color scheme is adopted in a control system, it must be consistent throughout.

For thermocouple and instrument wire color codes, see article.

Substitutions for the specified type of cable require approval by the responsible Electrical Design group unless identified “No Substitution.” All requests for substitutions and all approvals of substitutions shall be made in writing.

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